Lignin-Induced Click Synthesis of Au, Ag, Pd, and Iron Oxide Nanoparticles and Their Nanocomposites in Aqueous Bulk and at the Solid-Liquid Interface

Application of lignin in green click synthesis of Au,Ag, Pd, Au-Agbimetallic, Au-Ag-Pd trimetallic, and Fe3O4-Au-Ag-Pd nanocomposite nanoparticles(NPs) in aqueous bulk as well as at the solid-liquid interfacewas developed. Crossed-linked lignols of aqueous solubilized ligninor adsorbed at the solid-liquid interface acted as potentialelectron donors in click reduction of the metal center that dependedon the oxidation state, molecular geometry, and oxidizing abilityof electron-deficient species. Click reduction occurred in aqueousbulk and at the solid-liquid interface, which was a rapid andthermodynamically driven reaction at room temperature and did notdepend on reaction conditions such as pH and temperature. Quantitativeinformation was drawn by using UV-visible, DLS, and IR studies,whereas the elemental composition of different kinds of lignin-stabilizednanomaterials was determined by using TEM, FESEM, and XPS analyses.Au-Ag-Pd trimetallic NPs produced in aqueous bulk orat the solid-liquid interface because of the click reductionwere homogenously mixed at the solid-liquid interface but retainedthe core-shell in aqueous bulk. Lignin-stabilized Fe3O4-Au-Ag-Pd nanocomposite NPs werehighly responsive to the external magnetic field. They proved to beexcellent vehicles for quick and rapid extraction of KMnO4 from contaminated water, which was highly specific and sustainable. This study describes the role of ligninin click synthesisof sustainable nanomaterials in aqueous bulk and at the solid-liquidinterface suitable for environmental applications.